(a) Field of the Invention
The present invention relates to an apparatus and a method for controlling operation of a vehicle engine, and more particularly, to an apparatus and a method for controlling operation of an engine of a hybrid vehicle.
(b) Description of the Related Art
A hybrid vehicle (e.g., hybrid electric vehicle) refers to a type of vehicle that is driven by efficiently combining two or more different power sources. Generally, the hybrid vehicle uses a motor having a relatively good low speed torque characteristic as a main power source at a low speed and uses an engine having a relatively good high speed torque characteristic as a main power source at a high speed. Therefore, operation of an engine which uses a fossil fuel stops in a low speed section and a motor is used as a main power source, so that the hybrid vehicle is capable of improving fuel consumption and reducing exhaust gas.
Further, an operating point of a vehicle engine is determined based on a requested torque, a vehicle speed, and a gear stage in accordance with manipulation of a driver. For a hybrid vehicle, an operating point of an engine is determined based on a system optimal operating line (OOL) which is selected to minimize fuel consumption. The system optimal operating line is set based on efficiency at a representative temperature of each part (e.g., engine, motor, transmission, or battery). In other words, the system optimal operating line of the hybrid vehicle is selected based on efficiency in a full warm up state of the engine, efficiency in a full warm up state of a motor transmission efficiency of a full warm up state of a transmission, and charging and discharging efficiency at an optimal temperature of a battery.
In the meantime, when the vehicle travels on an actual road, efficiency of each part may vary due to deviation between vehicles, a travel distance of the vehicle, and surrounding circumstances such as an outdoor temperature (e.g., surrounding environment conditions). The system optimal operating line of the related art does not reflect the efficiency variation of each part (e.g., engine, motor, transmission, or battery), and thus the engine operating point determined based on the system optimal operating line may be determined in an incorrect area, rather than a region where the fuel consumption is at a lowest, thereby reducing the fuel consumption.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.